Paper has traditionally been the most convenient way to read and annotate documents, especially when a user annotates in natural handwriting, using a pen. Today, however, contemporary computing devices allow users to enter handwriting, such as by writing on the screen of a tablet or hand-held personal computer. Based on the technology that allows digital ink to be entered into a computer, computer applications have been developed that allow a user to annotate computer documents with digital ink annotations. As tablet and other handwriting-capable personal computers become more prevalent, traditional paper and pen-based annotating likely will become less common.
Current digital ink annotations are very similar to ink annotations on paper, comprising independent “mark-ups” or drawings, in which each annotation is treated as a singular entity whose positioning relative to the underlying document is preserved, maintained, and displayed, but whose content and/or meaning is disconnected from the document itself. As a result, any interpretation of the meaning of the annotation is left to the user's own cognition, even though the digital ink annotation may be as valuable as or even more valuable than the content within the annotated computer document.
One of the primary advantages of computer documents over paper documents is that users can conveniently and rapidly search for specific information within a computer-based document in ways that are not possible on paper documents. This has been done for a long time with text documents. However, because most computer applications treat digital annotations essentially as drawings, users do not have the ability to electronically search through the annotations added to computer documents. What is needed is a way to search computer documents that have been annotated with electronic ink, including searching the annotations.